JP4563108B2 - Method for manufacturing diaphragm for electroacoustic transducer, diaphragm and manufacturing apparatus therefor - Google Patents

Description

  The present invention relates to a method of manufacturing a diaphragm for an electroacoustic transducer, a diaphragm, and an apparatus for manufacturing the same.

  There are various types of diaphragms for electroacoustic transducers, but there are many pulp paper diaphragms that are lightweight and highly rigid. It is used.

  Although this diaphragm is manufactured through a papermaking process, a single-layered diaphragm can usually be manufactured in one papermaking process.

  However, as physical properties required for the diaphragm, elasticity, rigidity, internal loss, and the like are required, and it is difficult to obtain desired physical properties with a single-layer diaphragm made from one type of material.

  For this reason, various manufacturing methods have been proposed in which the diaphragm is formed by laminating layers having various functions to have a multilayer structure having performance that cannot be obtained by a single layer.

  As a method of obtaining this diaphragm, generally, a plurality of single-layer diaphragms are prepared, and these are bonded together with an adhesive to obtain a multilayer diaphragm.

  However, in this case, the adhesive layer between the layers constitutes a part of the diaphragm main body in addition to the original adhesive function, and the mass is increased. In many cases.

  For this reason, without using an adhesive, for example, as shown in Japanese Patent Laid-Open No. 48-29421, a multi-layer structure is formed at the paper making stage, and the layers are joined together by utilizing the entanglement during paper making between materials. Various types of wet multilayer papermaking diaphragms have been proposed in which the diaphragm is manufactured by heating and drying.

In addition, there are those obtained by separately making and heat-molding different materials.
JP 48-29421 A

  However, these have a problem that interlayer adhesion is insufficient, fatigue of the diaphragm occurs, and acoustic characteristics are insufficient.

  The present invention has been proposed in view of the above, and the object of the present invention is to provide a method for manufacturing a diaphragm having good adhesion, strong fatigue resistance of the diaphragm itself, and good acoustic characteristics, and thereby An object of the present invention is to provide a manufactured diaphragm and a manufacturing apparatus for manufacturing the diaphragm.

First aspect of the present invention, the first slurry was added to the paper making net 3 is the paper tube 2 provided below, a different material as the first slurry, and smaller specific gravity than the first slurry The second slurry is added immediately after the first slurry is added or after a predetermined time has elapsed, and the time difference between the start of papermaking of the first slurry and the introduction of the second slurry on the papermaking net 3 and the first 1. A diaphragm having an inclined structure in which the composition continuously changes in the thickness direction from the lower surface portion toward the upper surface portion using the specific gravity difference between the first and second slurries is produced.
The invention described in claim 2 is characterized in that a diaphragm is produced by the method for manufacturing a diaphragm for an electroacoustic transducer according to claim 1.
The apparatus according to the third aspect of the present invention includes a papermaking net 3 provided below the papermaking cylinder 2, and a papermaking head 6 provided above the papermaking net 3 and below the papermaking cylinder 2. The paper making head 6 includes a lower first circular portion 6a and a second circular portion 6b disposed on the upper side and having a smaller diameter than the first circular portion 6a. The first circular portion 6a has a step shape, and a small window 13 is provided on the outer periphery of the lower portion of the first circular portion 6a. It is characterized by being formed in plural.

  The present invention makes use of the difference in specific gravity of the slurry of different materials in the upper part and the lower part, and at the time of paper making, the slurry is first charged, and after the start of paper making, the time difference from the start of the next slurry having a different specific gravity is variable. A diaphragm having an inclined structure that can be controlled in a wide range can be created, taking advantage of the characteristics of different materials, and because the layers are not clearly separated, the problems of the adhesive described above are also improved, and the diaphragm itself is resistant to damage. The fatigue property is also strong, and good acoustic characteristics can be obtained.

  The present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of the apparatus of the present invention.

  In the figure, reference numeral 1 denotes a hollow papermaking mold, 2 denotes a papermaking cylinder provided above, and 3 denotes a papermaking net provided inside the papermaking mold 1. In the lower part of the papermaking mold 1, drainage means such as an evacuation adjusting valve 4 and a vacuum pump 5 are provided. 6 is a papermaking head provided in the papermaking cylinder 2 and above the papermaking net 3, 7 is a lower slurry introduced into the papermaking cylinder 2, and 8 is an upper slurry also introduced into the papermaking cylinder 2. is there.

  As for this lower slurry 7, the slurry in the first raw material tank 9 is injected into the paper tube 2 through the first regulating valve 10 for supplying the slurry.

  Thereafter, after a predetermined time has elapsed, the slurry placed in the second raw material tank 11 is introduced as the upper slurry 8 through the second adjustment valve 12.

  FIG. 2 shows an enlarged view of the papermaking head.

  The paper making head 6 has a circular shape when viewed from above, and includes a lower first circular portion 6a and a second circular portion 6b which is disposed on the upper side and has a smaller diameter than the first circular portion 6a. . A plurality of small windows 13 are formed on the outer periphery of the lower portion of the first circular portion 6a at appropriate intervals along the circumferential direction, and the lower and upper slurries 7 and 8 are passed through the small windows 13 to the paper network 3 side. It is configured to be introduced to. Thus, since the outer peripheral shape of the papermaking head 6 is formed in a stepped shape, the charged slurry slowly descends toward the bottom along the outer peripheral shape and flows to the papermaking net 3 side through the small window 13. Go.

  Next, a manufacturing example of the diaphragm will be described.

  As the lower slurry 7, mica having a large specific gravity and excellent sound velocity was used, and 10% LBKP was added as a binder. The solution concentration was 2 g / 1 L. The upper slurry 8 was made of non-wood bamboo pulp, and cut wool was added as 30% loss material. The solution concentration was 0.6 g / 1 L. The blending ratio of A and B is 25:75 by weight.

  Next, the papermaking mold 1 and the papermaking net 3 having a predetermined shape are set in the papermaking system. First, 2 L of sewage is introduced into the papermaking cylinder 2.

[Production Example 1]
FIG. 3A shows an example in which the paper making is started after the lower slurry 7 is charged, and the upper slurry 8 is charged immediately thereafter. In this case, as shown in the schematic diagram of FIG. 3 (a '), the lower and upper slurries 7 and 8 are instantaneously mixed in the papermaking cylinder 2, as if both the slurries 7 and 8 were mixed and stirred. It is close to the state where it was put in.

  The lower slurry 7 and the upper slurry 8 put into the paper making cylinder 2 have a small paper 13 in the lower part and a paper making head 6 whose outer shape is stepped, so that they immediately move to the paper making net 3 side. It gradually accumulates on the papermaking net 3.

  The lower slurry 7 and the upper slurry 8 in the papermaking cylinder 2 are compared with that of the upper slurry 8 as the time is passed from the start of papermaking, as shown in the schematic diagram of FIG. Due to the difference in specific gravity, it tends to gather slightly in the bottom direction and a slight inclination tendency appears, resulting in an inclined structure. A region indicated by a in FIG. 3B is the state of FIG.

  The graded structure refers to a state in which the lower slurry 7 and the upper slurry 8 do not form a clear layer, the composition changes continuously, and the respective materials are combined.

  Then, the mixture is deposited by the inclined structure on the deposit first deposited on the papermaking net 3 through the small window 13. Accordingly, as shown in FIGS. 3C and 3D, the slurry mixture in the papermaking tube 2 decreases.

  In the course of time in this process, the lower slurry 7 and the upper slurry 8 are further separated, and the ratio of the upper slurry 8 as the slurry in the papermaking cylinder 2 is increased, and this slurry passes through the small window 13 to form a deposit. Deposited on top.

  Thereafter, the deposited paper product is taken out, dehydrated, set in a molding die, heated, pressurized, dried, and taken out from the molding die, whereby a diaphragm having a desired shape can be produced.

  The white water that has flowed downward from the papermaking net 3 is discharged to the outside through a drainage system such as the regulating valve 4 and the vacuum pump 5.

  The diaphragm manufactured in this way has a lower slurry composition on the lower side (the rear side of the diaphragm), and an inclined structure with more upper slurry composition on the upper side (front side of the diaphragm) while continuously changing. Is forming.

  As described above, in the present invention, the wet papermaking method is applied to a method for manufacturing a diaphragm in which different materials are arranged in the thickness direction, and at least two kinds of materials having different physical properties and specific gravity are used. The slurry is fed into the paper tube 2 with a time difference and made up to produce a diaphragm in which the material slurry has a continuously inclined structure in the thickness direction from the upper surface to the lower surface due to the difference in specific gravity. It is characterized by doing.

[Production Example 2]
FIG. 4A shows an example in which papermaking is started after the lower slurry 7 is charged, and the upper slurry 8 is charged after 3 seconds. In this case, as shown in the schematic diagram of FIG. 4 (a ′), the upper slurry 8 is slightly less than the schematic diagram of FIG. 3 (a ′) due to the time difference of 3 seconds.

  The lower slurry 7 initially charged is deposited on the papermaking net 3 through the small window 13.

  As the papermaking time elapses, the slurry a portion in the papermaking cylinder 2 shown in FIG. 4 (b) forms an inclined structure as shown in the schematic diagram of FIG. 4 (b ').

  Then, this mixture is gradually deposited on the deposit on the papermaking net 3 with an inclined structure, and the slurry in the papermaking cylinder 2 decreases as shown in FIGS. 4 (c) and 4 (d).

[Production Example 3]
FIG. 5A is a diagram in which paper making is started after the well-stirred lower slurry 7 is charged, and the well-stirred upper slurry 8 is charged 5 seconds later. In this case, the material dispersed in the lower slurry 7 is considerably less than that of the upper slurry 8 as shown in the schematic diagram of FIG. As the papermaking time elapses, the portion of the slurry a in FIG. 5B forms a clear inclined structure as shown in the schematic diagram of FIG.

  In this way, the time difference from when the lower slurry 7 is charged to the start of papermaking and the time when the upper slurry 8 is charged, that is, the time lag, is controlled, and the gradient structure is variably controlled by utilizing the difference in specific gravity of the material. Is possible.

  According to this production example, the lower side of the diaphragm (the rear side of the diaphragm) is formed with the composition of the lower slurry 7, and the inclined structure with a large amount of the upper slurry composition on the upper side (the front side of the diaphragm) while continuously changing. It is the structure which formed and integrated.

  FIG. 6 shows a micrograph of the cross section of the diaphragm produced in Production Example 3.

  FIG. 7 shows the frequency characteristics of the diaphragm of the present invention having a 13 cm diameter manufactured using mica + LBKP: bamboo = 25: 75 (weight ratio).

  FIG. 8 shows the frequency characteristics of the diaphragm in Production Example 1 in which the same materials and blends as described above were used, and all the materials were mixed and stirred immediately before the material was added.

  Compared with the product manufactured in Manufacturing Example 3 and the product manufactured in Manufacturing Example 1, the product of Manufacturing Example 3 (FIG. 7) has no dip near 5000 Hz, and there is no excitement of sound pressure near 7000 Hz. It is a FLAT characteristic. It can be seen that, in terms of sound quality, noisiness at high frequencies disappears and good acoustic characteristics are obtained.

  In the above embodiment, mica is used as the material of the lower slurry 7, but the material is not limited to this. For example, AL, SUS, or the like may be used.

  The material used for the upper slurry 8 is not limited to non-wood fibers, and may be wood fibers.

  Moreover, although the example manufactured using two types of slurry was demonstrated, it is also possible to throw in the slurry 2 into the paper-making pipe | tube 2 from which another slurry from which a physical property differs further, and to produce a diaphragm.

  In addition, the slant structure is controlled by adding different slurries with a time difference. However, the slant structure can be controlled by adjusting the evacuation through the vacuum pump.

The structural example of the diaphragm manufacturing apparatus used by this invention is shown. The principal part expansion explanatory drawing same as the above is shown. (A)-(d) shows the flowchart of the manufacture example 1 of this invention, (a '), (b') shows the schematic diagram of a slurry. (A)-(d) shows the flowchart of the manufacture example 2 of this invention, (a '), (b') shows the schematic diagram of a slurry. (A)-(d) shows the flowchart of the manufacture example 3 of this invention, (a '), (b') shows the schematic diagram of a slurry. 6 shows a micrograph of a cross section of the diaphragm according to FIG. The frequency characteristic figure of the diaphragm of the manufacture example 1 of this invention is shown. The frequency characteristic figure of the diaphragm of the manufacture example 3 of this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Papermaking type | mold 2 Papermaking cylinder 3 Papermaking net | network 4 Adjusting valve 5 Vacuum pump 6 Papermaking head 6a 1st circular part 6b 2nd circular part 7 Lower slurry 8 Upper slurry 9 1st raw material tank 10 1st adjusting valve 11 1st 2 Raw material tank 12 Second regulating valve 13 Small window

Claims (3)

A first slurry is introduced into a papermaking cylinder (2) provided with a papermaking net (3) below, and a second slurry made of a material different from the first slurry and having a specific gravity smaller than that of the first slurry. Immediately after the first slurry is added or after a predetermined time has elapsed, and after the start of papermaking of the first slurry on the papermaking net (3), the time difference between the first slurry and the first, A diaphragm for an electroacoustic transducer, characterized in that a diaphragm having an inclined structure whose composition continuously changes in the thickness direction from the lower surface portion toward the upper surface portion using the specific gravity difference of the second slurry. Manufacturing method. A diaphragm for an electroacoustic transducer, wherein the diaphragm is produced by the method for manufacturing a diaphragm for an electroacoustic transducer according to claim 1. A papermaking net (3) provided below the papermaking cylinder (2), and a papermaking head (6) provided above the papermaking net (3) and below the papermaking cylinder (2). ,
The paper making head (6) has a lower first circular portion (6a) and a second circular portion (6b) disposed on the upper side and having a smaller diameter than the first circular portion (6a), The outer peripheral shape of the papermaking head (6) is stepped, and the slurry introduced into the papermaking cylinder (2) is spaced from the lower outer periphery of the first circular portion (6a) along the circumferential direction. An apparatus for manufacturing a diaphragm for an electroacoustic transducer, wherein a plurality of small windows (13) to be supplied to the papermaking net (3) are formed.

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